Separator for storage batteries and process of producing the same.



T. A. WILLARD. SEPARATOR FOR STORAGE BATTERIES AND PROCESS OF PRODUCINGTHE SAME.

APPLICATION FILED JUNE 30- 19M.

Patented Oct. 16, 1917.

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rnnononn A. wILLAnn, or CLEVELAND, onto.

SEPARATOR EOE STORAGE BATTERIES AND PROCESS OF PRODUCING THE E.

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' T all whom it may concern:

Be it'known that I, THEODORE A. WIL- LARD, a citizen of the UnitedStates, residing at Cleveland, in the county of Cuyahoga and State ofOhio, have invented a certain new and useful Improvement in Separatorsfor Storage Batteries and Processes of Producing the Same, ofwhich thefollowing is a full, clear, and exact description.

This invention relates to storage battery separators and to the processof making the same.

' A satisfactory separator should be formed of insulating material, andshould be sufficiently porous that the battery as a whole will have alow internal resistance, but the pores in this separator should besufliciently small and numerous that While they permit the batterysolution and current to pass freely through the separator, they shouldprevent the passage therethrough of the oxids of lead. Additionally, theseparators should be durable and have life co-extensive with the otherparts of the battery.

The best separators used heretofore are made of wood or hard rubber,although some have been made also from other materials such ascelluloid. The wood separator is perhaps the most efficient, but has aserious objection that it is not durable, its life being comparativelyshort. Rubber separators while more durable than the wood separators areexpensive, due chiefly to the necessity of perforating them, and havethe objection also that the perforations cannot be made suflicientlysmall or numerous to give the best results. Separators made of othermaterials, while-perhaps satisfactory in some respects are objectionablein other respects. For example, 'a separator of celluloid is veryinflammable, and for that reason its use is often prohibited.

The object of the invention is to provide a durable and inexpensiveseparator inwhich the pores or holes are very small and numerous, makinga very porous diaphragm of high conductivity.

In carrying out my invention, 1 provide a separator of suflicientlydurable material, such as rubber, and provide porosity prefverably'byembedding in the material composing the body of the separator and insucha manner as to extend from one side thereof Specification of LettersPatent.

Patented Oct. 16, 19117.

Application filed June 30, 1914. Serial No. 848,296.

to the other, material such as woven cloth, threads, hair, fiber and thelike which is porous, or other material which can under suitabletreatment be made porous.

These separators are preferably made by forming What may be termed acomposite block composed of some suitable binding or cementinglnaterial, such as rubber and the porosity yielding material such asabove mentioned, and thence by cutting, shaving, or sawing the blockinto sections of a thickness suitable for the separators or for formingthe separators, if the slices or sections are to be treated or shapedsubsequently to the severing thereof from the block. The block is out orsawed in such a way that a porosity yielding material will extendtransversely of the separator, or from face to face thereof, it beingunnecessary that it extend through the separator at right angles to thefaces or sides thereof.

My invention may be briefly summarized as consisting in a separatorhaving a certain construction and characteristics and in certain novelsteps'of the herein described process of producing the same.

In the accompanying sheet of drawings where T have shown separatorsformed in accordance with my invention and have illustrated the mannerin which they are formed, Figure 1 represents what I term the compositeblock from which the separators which are finally produced are cut,sawed or otherwise severed from the block; Fig. 2 is a similar viewillustrating the manner in which the separator sections may be severedfrom the block; Figs. 3 and 4 are perspective views respectively ofsections or layers of coarse woven cloth and plastic cementing material,a suitable number of which are superimposed and alternately arranged soas to form the composite block; Fig. 5 is a perspective view of aseparator section severed from the block; Fig. 6 is an enlarged view ofa portion of the block showing the superimposed and alternately arrangedlayers of cloth and rubber or other suitable cementing materialpreferably in 7 plastic state before the block has been compressed; Fig.7 is a similar view showing the same after compression and after theplastic material has been squeezed through and has filled the me hes orinterstices of the p0rosity yielding material; Figs. 8, 9 and 10 areperspective views of portions of separators constructed in accordancewith my invention, these views illustrating some of the numerous shapesthat the finished separator may assume.

Referring now to the figures of the drawings, 10 represents what I havepreviously termed a composite block which may be formed in anyindeterminate length, and having cross sectional dimensionscorresponding substantially to the Width and height of a storage batteryseparator. This block is built up of. superimposed layers or sheets 11of suitable cementing material, with porosity producing material, whichmay be-in the form of sheets 12, between the layers or sheets 11.Describing this block from a slightly difierent viewpoint, it is formedof alternately arranged sheets or layers of cementing material 11adapted to form the body of the separator and sheets or layers 12 whichare adapted to produce the pores through the body of the separator. Forthe material 11 I refer to use rubber or rubber compound, the materialsor ingredients of which are mixed so that hard rubber may eventually beproduced therefrom, and thence the compound is rolled into thin sheets,preferably of about 1/100 of an inch in thickness, which are cut toproper dimensions. I do. not Wish to confine my invention, however, tothe use of rubber, for as before stated other materials may be used,although I believe not so effectively as rubber. As examples of othermaterial which may be used, I might mention bakelite and celluloid.

For et'he porosity producing material I prefer to use a coarse wovencloth such as scrim, which is preferably cut on the bias, as illustratedin Fig. 3, and in sections of the same or substantially the same size asthe sections 11 which form the body of the block or of the separatorswhich are to be severed therefrom. Instead of using woven cloth I mayuse to good advantage haircloth, or I may use unwoven hair or unwoventhreads, strands, or fibers or the like. I may also use to advantagethin strands of wood or other fibrous material which it will 'beunderstood will be placed between the successive layers or sheets 11.The above mentioned materials are all more or less porous, but I do notwish to be confined to the same as I may employ non porous material,such as fine wire or wire gauze, which by suitable acid treatment willrender the separator porous, aS will be explained.

After the block is built up in the manner above described, it issubjected to pressure,

so that the material of the layers 11 will be squeezed in between thethreads or strands filling all the previously open interstices, and sothat the material of the layers '11 will be thoroughly united in a moreor less solid body in which is embedded the porosity producing material,and if rubber is utilized to form the body of the block, the latter isthen put into a vulcanizer and vulcanized either into soft or hardrubber, as desired, the layers being thoroughly vulcanized togetherthrough the interstices of the interposed porosity producing material.

Next, the block is shaved, cut or sawed into sections 13 of the properthickness for storage battery separators, the block being cut at rightangles-to the layers of which the block is built up or in planes atright angles to the planes of the porosity-produce ing layers ormaterial, so that extending through each separator section thus severedfrom the block there will be numerous minute threads or strands ofporous material. When strips or sections 12 of woven cloth are utilizedand are cut on the bias, as shown in Figs. 1 and 3, the threads whichextend through the separator sections severed from the block in themanner above described will not extend from face to face of theseparator section at right angles thereto, but will extend through thesection diagonally. This is preferred, although of course the threads orstrands may run from side to side of the separator section at rightangles thereto.

The separator sections severed from the block in the manner abovedescribed may then be molded in any desired shape, as

illustrated at 13, 13 and 13 in Figs, 8, 9 and 10, and will bevulcanized (if necessary) so as to produce hard finished separators,each of which will be a very porous diaphragm having pores of any sizerequired down to the most minute threads.

As before stated, the block may bevulcanized into hard rubber, orassuming that bakelite or other material than rubber is utilized, theblock may be formed into a permanent hard state before it is cut orsevered into the separator sections. The block will then be sliced orsawed and the surfaces of the sawed separators may be ground to produceribs (if desired), or the separator sections may be left flat and ribsmay be molded or attached to the surface or surfaces.

It will be understood that the finished separator may be formed intoother shapes than here illustrated. For example,'it may be in the formof a receptacle to hold a plate or a portion of a plate or an electrode,or it may be formed and used as a porous diaphragm in any part of thebattery requiring such materials.

As before stated, wood strands may beutilized instead of the woven clothto produce the pores in the separator. Such separator, corresponds inutility to the regular ees,

taining wood is a perfect support for the wood allowing the woodingredient or filling to be used up to its utmost limit of lifethroughout which it will possess the necessary mechanical strength.

The separator containing the inert porous material above described maybe treated in a solution of acid or acids to render the inert materialsoft and more porous than in its natural state, although the separatorswill have high efficiency without such treatment. For example, the majorportion of the porous materlals above mentioned may be converted intocellulose or carbon by treating the separator with the proper kinds ofacids. If the separator is thus treated it will subsequently be affectedvery little by the acid used in the battery solution. In the event thatI use for the porosity producing material, material which originally isnot porous, such as metal gauze or fine steel wire, to render theseparator porous, it will be treated with acid such as sulfuric acidwhich will dissolve out the fine strands of metal leaving minute pores.

By the above process I am able to produce a separator which I believe tobe superior to anything which has heretofore been used. The separator isnot only extremely porous, but the pores are exceedingly fine and it ispossible to increase the number of pores or perforations to the maximumwithout material danger of breakage.

In a companion application, Serial No. 5,588, filed February 1, 1915 forstorage battery separators and process of producing the same, I havedisclosed a separator and a process which in certain respects aresimilar to the separator and process of this application. Inthecompanion application referred to, the block or body from which theseparator sections are cut, instead of being formed from alternatelayers of rubber and pore producing material as disclosed in this case,is formed from pore producing material Which is coated or impregnatedwith rubber or cementitious material.

Having thus described my invention, what I claim is z- 1. A storagebattery separator composed of a binding material and porous materialextending from side to side through the separator and forming apermanent part thereof.

' 2. A separator blank for storage batteries having porosity producingmaterial extending substantially uniformly from side to side through thesame.

3. A separator blank for storage batteries comprising a body containingpore producing material extending substantially directly from side toside through the same.

4. A separator for storage batteries composed of non porous mate'rialand finely divided pore producing material extending in substantiallty'straight lines from side to I side thereo 5. A separator for storagebatteries formed from hardened lastic material and. pore producinmateria extending substantially uniform y through the separator.

6. A separator for storage batteries formed from rubber compound andclosely arranged porous material extending in. a general direction fromone side of the separator to the other.

7. A separator for storage batteries composed of non-porous materialrendered porous by the presence of finely divided porous materialarranged in layers.

8. A separator for storage batteries formed of non porous bindingmaterial and porous material consisting of strands whose ends areexposed and substantially uniformly distributed over the sides of theseparator.

9. A storage battery separator composed of porous material extendingfrom side to side through the separator, and a cementing material.

10. A storage battery separator composed of porous material extendingtransversely therethrough, and rubber as a binding agent.

11. A storage battery separator composed of threads extendingtransversely therethrough, and rubber as a binding agent.

12. The method of producing separators for storage batteries whichconsists in embedding in a mass of separator material, material forproducing pores and cutting said mass into separator sections.

13. The method of producing separators for storage batteries whichcomprises forming a composite body of non-porous material and porousmaterial, and cutting the body into sections suitable for theseparators.

14. The method of producing separators for storage batteries whichcomprises forming a body of binding material and material for formingpores and cutting the body into sections so that the pore forminmaterial will extend from side to side t rough the sections.

15. The method of producin separator blanks for storage batteries whiccomprises forming a body of rubber compound and pore producing materialand cutting said ody into separator sections in such a manner thatthepore producing material extends through the sections from side toside thereof.

16. The method of producing separators for storage batteries whichcomprises forming a body from binding material and closely arrangedporous material, and slicing said body in parallel, planes so as toproduce fiat separator sections having the porous material extendingfrom side to side through the same,

- 17. The method of roducing separators a binding material, and. slicingthe body into 10 for storage batteries w ich comprises formsections atright angles to the layers. ing a composite body of porous material andIn testimony whereof, Ihereunto afiix my non orous material, and slicingthe body signature in the presence of two Witnesses.

5 at su stautially right armies to the porous materiaL THEODORE A.WILLARD.

18. The method of roducing separators Witnesses: for storage batteries wich comprises form- L. I. PORTER,

ing a body of layers of porous material and A. F. KWIS.

